Method of improving oxidative stability of fluorosilicone fluids

ABSTRACT

THE INVENTION DESCRIBED HEREIN IS A LUBRICATING COMPOSITION CONTAINING ANTIMONY TRIOXIDE IN A LIQUID CARRIER AND IS ESPECIALLY SUITABLE FOR THE LUBRICATION OF TITANIUMSTEEL AND MONEL-STEEL INTERFACES. ADDITIONALLY, IT HAS BEEN FOUND THAT THE ADDITION OF ANTIMONY TRIOXIDE TO FLUOROSILICONE FLUIDS TENDS TO STABILIZE SUCH FLUIDS AGAINST OXIDATION.

United States Patent 3,629,106 METHOD OF IMPROVING OXIDATIVE STABILITY OF FLUOROSILICONE FLUIDS George J. Quaal, Midland, Mich., William L. Schaefer,

Palatine, Ill., and Robert J. Kelly, Bridgeport, Mlch., as-

signors to Dow Corning Corporation, Midland, Mich. No Drawing. Filed May 21, 1969, Ser. No. 826,725

Int. Cl. Cm 3/46, 3/02 US. Cl. 252-25 2 Claims ABSTRACT OF THE DISCLOSURE The invention described herein is a lubricating composition containing antimony trioxide in a liquid carrier and is especially suitable for the lubrication of titaniumsteel and Monel-steel interfaces. Additionally, it has been found that the addition of antimony trioxide to fluorosilicone fluids tends to stabilize such fluids against oxidation.

BACKGROUND OF THE INVENTION This application relates to lubricating compositions containing solid lubricant materials and more particularly to compositions for lubricating titanium-steel and Monelsteel interfaces.

It has been known for many years that certain solid materials such as graphite and molybdenum disulfide, for example, are excellent lubricating materials both when applied in a dry form as by rubbing and when incorporated in a liquid carrier to the bearing surfaces. Of course, liquid lubricating materials such as mineral oils and silicone oils, for example, are also well known. No material, however, provides freedom from friction, and research goes on for better lubricating materials.

One area of lubricant application, which has been an extremely diflicult one, is the lubrication of titanium against steel in the drawing of titanium tubes and during titanium tapping. While commercially available materials are presently used for this application, they leave much to be desired. Interfaces between Monel and steel also suffer from lack of a good lubricating material, particularly, for example, in the drawing of Monel wires through steel dies.

US. Pat. No. 3,223,626 describes a resin-bonded solid film lubricant designed to provide good corrosion inhibiting properties on zinc-phosphatized steel. These resinbonded systems include epoxy-phenolic resins or silicone resins which incorporate a substantial amount of molybdenum disulfide and include a relatively small percentage of antimony trioxide. While resin-bonded systems certainly have application in areas where permanent lubrication is required, such systems are useless or virtually useless in areas such as tube drawing and wire drawing or metal tapping.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, it is generally an object of the present invention to provide an improved composition for lubrication of metals.

It is a further object of the present invention to provide lubricating compositions and methods for lubricating titanium.

A still further object is to provide a lubricating composition and methods for lubricating Monel.

In accordance with these and other objects, there is provided by the present invention a lubricating composition comprising between 10 percent and 80 percent by weight of particulate antimony trioxide substantially uniformly dispersed in a liquid carrier which comprises at least 20 percent by weight of the composition. The liquid carrier can be any of the mineral oils, silicone fluids, fluorosili- "ice cone fluids, phosphate esters, fluorocarbon oils, dibasic acid esters, glycerin and glycols. In addition to the antimony trioxide, other solid lubricant particles can be added to the composition. T itanium-steel and Monel-steel interfaces can be lubricated by applying to said interfaces the aforesaid lubricating composition.

Friction wear tests using the aforesaid compositions show that a very low coeflicient of friction and a very low 'wear rate result from the use of these materials. While these lubricating compositions have general application in the field of lubrication, it has been found that they are particularly valuable in metal working of Monel and titanium, using steel tools.

Somewhat surprisingly, during the work in testing the compositions and methods of the present invention is was also found that the oxidative stability of fluorosilicone fluids is improved greatly by the addition of the antimony trioxide particulate matter. While the fluorosilicone fluids have heretofore found application as lubricating materials, they have been hampered by low thermal oxidative sta bility. In applications where there is substantial heat buildup, a fluorosilicone volatilizes in oxidizing atmospheres and loses its effectiveness. By adding antimony tri-' oxide to the fluorosilicone fluid in amounts between about 10 percent and 300 percent by Weight of the fluid, the fluid Weight loss at temperatures on the order of 450 F. is reduced substantially from that which results when the fluid is used alone. Therefore, in the fluorosilicone fluid based compositions of the present invention, one obtains both the lubricating qualities of the antimony trioxide as a film-forming, solid lubricant in the composition and the liquid lubrication provided by fluorosilicone fluids.

Other objects and attendant advantages will become apparent to those skilled in the art from the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the present invention, there is provided a lubrication method in which a composition containing between about 10 percent and percent by weight of particulate antimony trioxide is substantially uniformly dispersed in a liquid carrier which comprises at least 20 percent by weight of the composition. Suitable liquid carriers include mineral oils of various types, silicone fluids (organopolysiloxanes), fluorosilicone fluids (fluorinated organopolysiloxanes), phosphate esters, fluorocarbon fluids, dibasic acid esters, glycerin and glycols such as ethylene glycol.

The composition is made simply by mixing the antimony trioxide into the liquid carrier. In low concentration of solids, the resulting material is simply a fluid or oily composition in which the solid particles are suspended. In higher concentrations, the resulting composition becomes a grease or a lubricating paste depending upon the lubricity of the fluid itself and the concentration of solid particles therein.

In addition to the antimony trioxide, it has been found that other solid lubricant particlescan also be included in the composition. Such materials include, for example, M052, W82, W832, Nbseg, Nbsg, Ca(OH) 211F207, CaO, graphite and AlPO The liquid carrier suitable for use in the present invention may be chosen from the group consisting of mineral oils, silicone fluids, fluorosilicone fluids, glycerin and glycols. Suitable mineral oils include, for example, white mineral oil, petroleum oils and commercial petroleum oil compositions.

The silicone fluids are organopolysiloxanes and may include, for example, dimethylpolysiloxane fluids and phenylmethylpolysiloxane fluids, among others.

The fluorosilicone fluids include such fluids as trifluoropropylsiloxanes, and mixtures of trifluoropropylmethylsiloxanes and dimethylsiloxanes.

Suitable glycol fluids include any of those fluids commonly used as lubricant dispersion carriers such as, for example, ethylene glycol.

The resulting compositions were found to be excellent lubricants in a variety of situations and are particularly excellent lubricants in the lubrication of titanium-steel and Monel-steel interfaces. The titanium and Monel lubrication is particularly useful in the fields of wire drawing, tube drawing, tapping and other forms of metal working where lubrication has been heretofore a particularly difficult problem.

In addition, other commonly used lubricant additives can be incorporated into the composition in small amounts.

It has been known heretofore that the fluorosilicone fluids are reasonably good lubricants for certain applications. A problem, however, has existed in the use of these materials at high temperatures; that is, on the order of 400-450 F. At these temperatures these materials tend to degrade due to oxidation and volatilize from the bearing surfaces.

It has been found that the addition of antimony trioxide in the quantities suitable for the lubricating composition of the present invention has enhanced the thermal oxidative stability of the fluorosilicone composition. While this eflect is notable over the entire range of the composition, it has been found to be optimum in the range of 40 to 60 percent antimony trioxide in the composition; that is,.the addition of antimony trioxide in an amount between 80 percent and 120 percent of the weight of said fluid provides optimum stabilization. Greater weight losses of fluid at around 450 F. are observable when the concentrations fall above or below this range.

The invention will become better understood to those skilled in the art from the following specific examples of lubricating methods and compositions according to the present invention and comparison with prior art compositions under similar conditions.

EXAMPLE 1 Compositions were prepared by mixing in accordance with the following table:

Percent Sample No. Fluid carrier Sbz03 Other additives A 29, White mineral oil 71 {27.5, White mineral oil I; 12. 8 7 .7,ZnP2O B 15.4, lithium grease 38.4,Ca(OH2).

1.6, metallic soap ester. 1.6, synthetic wax. C 89, petroleum oil 10 1, DuPont LOA 565. D 31, glycerin 69 E 31, silicone glycol 69 F 32, ethylene glycol" 68 G 68 68 cs.) 60 .T 40, trifluoropropyl methylpolysiloxane (10,000 as). 60 K 39, trifiuoroproply methylpolysiloxane (300 05.). 61 L 39.2, trifluoroproply methyl- 9.8, PbPO polysiloxane. 24. 2.0, SiOz.

24.5, lVIOSz.

All percentages in the above formulations are by Weight.

Tests were made by comparing tapping torque in titanium with Cutzol 400-A, a commercial cutting coolant used extensively on titanium and sold by Rust-Lick, Inc. of Boston, Mass. With the torque required to tap using this material as 100 percent, the tapping efficiency of the above samples under identical conditions was as follows: C=100%; D=141%; E=162; F=163%; G:135%; H=139%; J=173%; K:139%; L=202%.

Tests were made on the Alpha LFW1 test machine in oscillating mode. Using a standard steel ring and R 4 steel block at 10 are, 75 cycles per minute, Sample I gave a wear scar of 0.8 mm. after 5000 cycles at 150 lb. load.

Using an R 30 steel block and a titanium alloy Ti6Al-4V test ring, after 5000 cycles at 150 pound load, the wear scar on the block using Sample A was 0.5 mm., and the coefficient of friction during test was measured at 0.097. For Sample B under the same conditions, the coefiicient of friction was measured as 0.083: the resulting wear scar was 0.4 mm. Sample A was also tested using an R 30 steel block and Monel ring. After 5500 cycles, a Wear scar of 0.3 mm. in length was observed on the block.

EXAMPLE 2 A mixture of (by weight) 37.4 percent trifluoropropylmethylpolysiloxane (1,000 cs.), 56 percent Sb O 4.7 percent PbPO and 1.9 percent SiO (Mixture 1) was tested in comparison with an identical mixture wherein M08 was substituted for the Sb O (control). In the LEW-1 oscillating test as described in Example 1 using steel on steel, the wear scar after 5000 cycles was 0.9 mm. for Mixture 1 and 1.4 mm. for the control. Similarly, on the LEW-4 E. P. Press Fit test (ASTM) at low speed (0.6 in./min.), Mixture 1 showed a friction coefiicient of 0.14 and percent entry while the control failed at 32 percent entry. In the Falex wear test, Mixture 1 showed a maximum jaw load to high wear rate at 900 pounds, whereas the control showed a maximum jaw load to high Wear rate at 600 pounds.

EXAMPLE 3 A comparative test of weight loss for fluorosilicone fluid (trifluoropropylmethylpolysiloxane 10,000 cs.) under 450 F. atmospheric conditions for a 14-day period was made for compositions containing (by weight) no Sb O and 40 percent Sb O The percentage weight loss in the fluid with no additive was 41.1 percent, while that of the filled fluid was 34.8 percent of the fluid alone.

Other variations and modifications will become obvious to those skilled in the art from a reading of the foregoing. It is to be understood, therefore, that the specific examples given above are solely exemplary of the invention.

That which is claimed is:

1. A method of enhancing the thermal oxidative stability of fluorosilicone fluids comprising adding antimony trioxide to said fluids in amounts between 10 percent and 300 percent of the weight of said fluid.

2. A method as defined in claim 1 wherein the amount of said antimony trioxide added is between 80 percent and percent of the weight of said fluid.

References Cited UNITED STATES PATENTS 748,317 1903 Smith 252-25 2,652,362 9/1953 Woods et a1 252-33.6 2,717,221 9/1955 Christner 252-18 2,990,373 6/1961 Ragborg 252-25 3,223,626 12/1965 Murphy et a1. 252-25 3,239,462 3/1966 Bergstrom et al 252-33.6 3,288,710 11/1966 Hollitz 252-25 3,300,667 1/1967 Boes et a1 252-25 3,314,889 4/1967 Christian 252-49.6 3,390,562 7/1968 Rausch et al 252-18 3,361,666 1/1968 Gaddis et al 252-30 FOREIGN PATENTS 604,204 11/1963 Canada 252-25 774,098 12/ 1967 Canada 252-25 DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. or. X.R. 252-49.6, 397

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CURRECTION PATENT NO. 3,629,106

DATED I December 21, 1971 INVENTO I George J. Quaal et a1.

It is certified that error appears in the above-identified patent and that said Letter s Patent are hereby corrected as shown below: a

In column 2, line 15, the word "is should read --it.

In column 3, line 17, after the word "amounts. add the sentence --Such materials include, for example,

anticorrosive materials and synthetic resin .particles.-.

In column 3, line 72, "E=l62;" should read E=l62%;.

fiigned and geakd this Fifth Day of Mayl98l [SEA L] Amen:

RENE n. 'iEGTMEYER Arresting Oflicer Acting Commissioner of Patents and Trademarks UNITED STATES PATENT AND! TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. r 3,629,106

D E 1 December 21, 1971 INVENTOR( 1 George J. Quaal et a1.

it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 2, line 15, the word "is" should read --it--.

In column 3, line 17, after the word "amounts. add the sentence -Such materials include, for example,

anticorrosive materials and synthetic resin .particles..

In column 3, line 72, "E=l62;" should read -E=l62%;--.

[SEAL] Arrest:

RENE D. TEGTMEYER Arresting Oflicer Acting Commissioner of Patents and Trademarks 

